Guth B D, Miura T, Thaulow E, Heusch G, Ross J
Department of Medicine, University of California, San Diego, La Jolla.
Basic Res Cardiol. 1993 May-Jun;88(3):282-96. doi: 10.1007/BF00795000.
The effect of selective alpha 1-adrenoceptor blockade on regional myocardial blood flow and contractile function during exercise-induced myocardial ischemia was determined in nine dogs having chronic single vessel coronary stenosis (ameroid constrictor). Treadmill exercise performed after beta-adrenoceptor blockade (1.0 mg/kg i.v. propranolol), to block potential prejunctional effects recently recognized with alpha-blockade, elicited severe regional myocardial ischemia with a steady-state reduction of regional systolic wall thickening of the post-stenotic myocardium from a resting value of 21.8% to 7.0%. Blood flow to the ischemic subendocardium was reduced from 0.76 to 0.36 ml/min/g (microspheres). Prazosin (80 micrograms/kg i.v.) was administered during continued running, and angiotensin II was simultaneously infused to prevent the decrease in systemic arterial pressure caused by prazosin. During the subsequent steady state, with arterial pressure matched to the pre-prazosin level, regional subendocardial blood flow improved to 0.60 ml/min/g and systolic wall thickening in the post-stenotic region increased modestly to 10.2%. No changes in blood flow to the outer portion of the post-stenotic region or to the remote control region were seen, and prazosin caused no effect on regional function in the control area, indicating effective blockade of prejunctional effects of prazosin (demonstrated in pilot studies). The finding that blockade of alpha 1-adrenoceptors resulted in improved ischemic zone subendocardial blood flow and contractile function are consistent with alpha 1-adrenoceptor-mediated reduction of blood flow to the ischemic subendocardium during exercise-induced ischemia in dogs with beta-blockade.
在9只患有慢性单支冠状动脉狭窄（阿梅里德缩窄器）的犬中，确定了选择性α1 -肾上腺素能受体阻断对运动诱导的心肌缺血期间局部心肌血流和收缩功能的影响。在β -肾上腺素能受体阻断（静脉注射1.0 mg/kg普萘洛尔）后进行跑步机运动，以阻断最近认识到的α阻断的潜在节前效应，引发了严重的局部心肌缺血，狭窄后心肌的局部收缩期壁增厚从静息值21.8%稳定降低至7.0%。缺血性心内膜下血流从0.76降至0.36 ml/min/g（微球）。在持续跑步期间给予哌唑嗪（静脉注射80μg/kg），同时输注血管紧张素II以防止哌唑嗪引起的体动脉压下降。在随后的稳定状态下，动脉压与哌唑嗪给药前水平匹配，局部心内膜下血流改善至0.60 ml/min/g，狭窄后区域的收缩期壁增厚适度增加至10.2%。未观察到狭窄后区域外部或远程对照区域的血流变化，且哌唑嗪对对照区域的局部功能无影响，表明哌唑嗪的节前效应被有效阻断（在前期研究中得到证实）。α1 -肾上腺素能受体阻断导致缺血区心内膜下血流和收缩功能改善的发现与在β阻断的犬运动诱导缺血期间α1 -肾上腺素能受体介导的缺血性心内膜下血流减少一致。
